Placental issues Flashcards
Describe the types of cord insertion (6 types). For each
-Definition
-Incidence
-Risk factors
- Velamentous
- cord vessels are separate before insertion
-Incidence 1% - Marginal cord insertion
- cord inserts in or near the margin of the placenta
-7-9%.
-Increased in twin pregnancies. PTL, IUGR, Fetal distress - Succenturiate
- placenta has 1 or more smaller lobe with exposed vessels running between the two
-Incidence - 5%
-Risk factors - Advanced maternal age, IVF, fibroids, Vasa praevia - Bilobate - placenta is bilobed with no exposed vessels between the two lobes. Lobes are roughly the same size.
Incidence - 2-8%
Risks - increase in abruption, polyhydramnios, retained placenta - Circummarginate
-Extrachorial, annular shape with raised edges composed of a double fold or the chorion. Smaller basal plate.
-PPROM, PTB, Placental insufficiency - Circumvallate
-Extrachorional placenta similar to the circummarginate except the transition to the membranous to villous chorion is flat.
Discuss fetomaternal haemorrhage
-Definition
-Causes (3)
-Clinical features (5)
-Investigations (3)
- Definition
Haemorrhage of fetal cells into maternal circulation - Causes
-Most of the time no cause is found
-Abruption
-Trauma - Clinical features
-Nil
-APH
-Reduced FM
-Symptoms of transfusion reaction in mother is ABO incompatibility
-IUFD - Investigations
-Kleihauer-Bekte test
-MCA PSV >1.3 MoM = moderate anaemia, >1.5 MoM = severe anaemia
-Cord blood haemoglobin (Cordocentesis)
Discuss limitations of the kleihauer bekte test.
1. With the test
2. With the results
- Limitations with the test
-Manual counting technique
-Technically challenging
-Interobserver variation
-Variable staining which impacts cell counting - Limitations with results
-Is based on an assumption of maternal blood volume so over estimates in small women and under estimates in large women
-Lifespan of fetal RBC are reduced in maternal circulation with ABO incompatibility
-Only 4% of abruptions have +ve kleihauer
-FMH doesn’t equal abruption and vise versa
Discuss unexplained APH
-Risks (6)
-Management
- Risks
-PTB OR 3.0
-Still birth OR 2.10
-Fetal anomalies OR 1.42
-NICU admission
-Hyperbilirubinemia
-Lower BW - Management
-If spotting only and placenta praevia excluded can be discharged home
-If anything heavier admit for observation at least until stopped
Discuss Vasa praevia
-Definition (2)
-Classification (2)
-Risk factors (4)
-Incidence (1)
- Definition
-Passage of fetal vessels within free placental membranes within 2 cm of the internal cervical os
-Vessels are not protected by placental tissue or Wharton’s jelly - Classification
Type I - vessel is connected to velamentous umbilical cord
Type II - vessel connects the placenta with a succenturiate or accessory lobe - Risk factors
-Placenta praevia - OR 22
-Bilobed/Succenturiate lobe OR 22
-Velamentous cord insertion - occurs in 2%
-ART OR 8
-LLP in the third trimester - Incidence
-1:2500
Discuss diagnosis of vasa praevia
-Screening (5)
-USS features (4)
-Confirmation (2)
- Screening
-No evidence to support universal screening
-RANZCOG supports universal screening of cord insertion at mid trimester scan but not routine TVUSS for vasa praevia
-Targeted screening in those with risk factors for vasa praevia with TAUSS then TVUSS if concerning features (RCOG doesn’t recommend - insufficient evidence)
-Need to use colour doppler and TVUSS to confirm. (High sens and spec 100% & 99.8%. Most accurate method RANZCOG)
-Best done 18-20 weeks with confirmation at 30-32 weeks
-If risk factors then consider TVUSS on midtrimester scan - USS features
-Aberrant liner or tubular echolucent structure
-Blood flow within these structures on doppler
-Umbilical artery/venous wave form on pulse doppler
-Aberrant vessel or vessels located within 2cm of internal os attached to the inner perimeter of the fetal membranes - Confirmation
-If seen in 18-20 weeks scan repeat scan at 30-32 weeks
-Resolution occurs in 20%
Discuss antenatal management of vasa praevia (11)
- Tertiary referral
- Prophylactic hospitalisation from 30-32 weeks (RANZCOG)
- If considering outpatient management a long closed cervix and negative FFN would be reassuring but not evidence based
- Role of cervical length and cerclage is unknown
- Steroids at 32 weeks as precaution for rapid delivery
- Aim delivery 34-36 weeks. Never after 37 weeks
- Immediate CS if PPROM or labour or suspected bleeding from fetal vessels. Have O neg blood available
- If SROM with bleeding and fetal distress consider vasa praevia and deliver. Don’t await Dx
- Aim delivery in a hospital with appropriate neonatal resus ability
- Delivery is by CS with mapping of fetal vessels to avoid laceration
- Send placenta for histo in event of still birth or neonatal death
Discuss possible clinical manifestations of vasa praevia (3)
- Dx on USS
- Palpation of pulsating fetal vessels at internal os on VE
- Dark red vaginal bleeding and acute fetal compromise after SROM or ARM
Discuss management of vasa praevia when undiagnosed on USS (4)
- Cat 1 section. Do not wait for diagnosis
- Inform paeds
- Neonatal resus probable
- Neonatal blood transfusion with O neg blood likely
What is the fetal prognosis with vasa praevia
-Overall mortality
-Mortality when dx by USS antenatally
-Mortality if undiagnosed antenatally
- Overall mortality - 36%
- Mortality with antenatal dx - 3%
- Mortality without antenatal dx 66%
Discuss placenta praevia
-Incidence (4)
-Classification (3)
-Risk factors (8)
- Incidence
-1:5 at 24 weeks
-1:200 at term
-1:100 if previous CS - RR4.5
-3:100 if 3 previous CS - RR 6.5 - Classification
-Can be assessed if >16 weeks
-Placenta praevia = covering internal os
-Low lying placenta = within 2 cm of internal os - Risk factors
-Smoking OR 1.4
-IVF pregnancy OR 3.7
-Previous D&C
-Previous CS esp if done pre labour or less than 12 months ago. Dose response
-Previous placenta praevia - risk recurrence 4-8%
-Multiparity
-AMA
-Multiple pregnancy
Discuss placenta praevia
-Who and when should there be screening (4)
-What are the chances of resolution (2)
-What factors make resolution less likely (3)
-What is the role of cervical length (2)
- Who and when should there be screening
-All women should have placental location documented at routine anatomy scan
-Screen if APH
-Repeat scan at 32 weeks as 90% will have resolved
-Repeat scan at 36 weeks as another 50% will have resolved - Factors which make resolution / migration less likely
-Previous CS
-Posterior placenta
-If placenta >2.5cm over internal os - Role of cervical length
-Short cervix (<30mm) <34/40 is predictive of increased risk of haemorrhage and PTB.
-Impact of a cerclage is unknown and not recommended
Discuss placenta praevia
-Maternal risks (4)
-Fetal risks (5)
- Maternal risks
-PPH
-Hysterectomy
-DIC
-AKI - Fetal risks
-Prematurity and associated perinatal morbidity
-Cord prolapse from malpresentation
-IUGR
-Anaemia from exsanguination if placenta incised during CS
-Fetal mortality - 8:100
Discuss presentation of placenta praevia
-Bleeding (6)
-Pain (2)
-Examination (2)
- Bleeding
-30% bleed before 30/40
-30% bleed 30-36/40
-30% bleed >36/40
-10% bleed in labour
-Precipitated by shearing forces on placental vasculature - sexual intercourse.
-Often unprovoked - Pain
-Bleeding is usually painless
-Can be associated with contractions either prior to onset of bleeding or post bleeding from uterine irritability - Examination
-Anyone with bleeding and high presenting part need to rule out placenta praevia
-Don’t do a VE
Discuss antenatal management of placenta praevia (9)
- Optimise Hb
- Ensure up to date G&H with blood put aside if difficult crossmatch
- Advise to avoid sexual intercourse or travel far from medical assistance
- Advise to present if contractions, bleeding, pain
- Consider steroids (RCOG single dose 34-35+6)
- Serial growth scans if APH
- TEDS and mobilisation for thromboprophylaxis
- Individualise location of care based on pregnancy circumstances and social circumstance
- Consent and advise around risk of hysterectomy (2% if praevia, 10% if praevia + prev CS)
- If presenting in PTL with PVB but stable tocolytics can be considered